Human Capabilities SE3830 - Jay Urbain, PhD Credits: Card, Moran, Newell, The Psychology of Human-Computer Interaction , Lawrence Erlbaum Associates, 1983. Prof. Robert Miller, MIT Department of Electrical Engineering and Computer Science. Donald Norman, Design of Everyday Things
User interface hall of shame? • Looking for contributions! Eye Tracking! • http://online.wsj.com/article/SB100014241278873241052045783823 53581452288.html?mod=WSJ_hp_EditorsPicks • http://www.tobii.com/group/news-and-events/tobii-in-media/tobii- presents-eye-controlled-laptop/ • http://www.nytimes.com/2011/03/27/business/27novel.html?ref=busi ness • Andrew T. Duchowski, a professor of computer science at Clemson University, and author of the book “Eye Tracking Methodology.” • Kinect - Ontology surgeons bring video game technology to the OR http://www.ctv.ca/CTVNews/Health/20110318/surgeons-kinect- 110318/
Introduction • This course is about building effective human-computer interactions. We've talked about: • Usability. • Guidelines, principles, and theories. • Evaluating interface designs. • What about the properties of the system we are designing for?
Introduction • We should understand the properties of the system we are designing for. – Speed, memory size, hard disk, operating system, and the interaction between these in the computer system . – Processors, memories, and properties of the human cognitive apparatus we are designing an interaction for.
Topics • Human information processing • Perception • Motor skills • Memory • Decision making • Attention • Vision
Hierarchical temporal memory (HTM) • Machine learning model (Jeff Hawkins and Dileep George) that models some of the structure and algorithmic properties of the neocortex . • HTM is a biomimetic model based on the memory- prediction theory . • HTM combines and extends approaches used in Bayesian networks , spatial and temporal clustering algorithms, while using a tree-shaped hierarchy of nodes that is common in neural networks .
Memory-prediction Framework • The central concept of the framework is that bottom-up inputs are matched in a hierarchy of recognition. • Evoke a series of top-down expectations encoded as potentiations. • These expectations interact with the bottom-up signals to both analyze those inputs and generate predictions of subsequent expected inputs.
Model Human Processor Developed by Card, Moran, and Newell as a way to summarize decades of psychology research in an engineering model . ( The Psychology of Human-Computer Interaction , Lawrence Erlbaum Associates, 1983).
Model Human Processor (MHP) • This model is an abstraction, but provides us with numerical parameters describing how we behave. • Just as a computer has memory and a processor , so does our model of a human. • The model has several different kinds of memory, and several different processors.
MHP - Memory • Input from the eyes and ears is first stored in the short-term sensory store . • The perceptual processor takes the stored sensory input and attempts to recognize symbols in it: letters, words, phonemes, icons. • It is aided in this recognition by the long-term memory , which stores the symbols you know how to recognize.
MHP - Cognitive Processor • The cognitive processor takes the symbols recognized by the perceptual processor and makes comparisons and decisions. • It might also store and fetch symbols in working memory (RAM). • The cognitive processor does most of the work that we think of as “thinking”.
MHP - Motor Processor • The motor processor receives an action from the cognitive processor and instructs the muscles to execute it. • There’s an implicit feedback loop here: – the effect of the action can be observed by your senses, and used to correct the motion in a continuous process. • Finally, there is a component corresponding to your attention , which might be thought of like a thread of control in a computer system.
Memories Each memory has properties • Encoding: type of things stored • Size: number of things stored • Decay time: how long memory lasts
Short Term Sensory Store - VIS • Visual information store (VIS) – encoded as physical image – size ~ 17 [7-17] letters – decay ~ 200 ms [70-1000 ms] – Basically a framebuffer for the eyes. – Instead of being encoded as pixels, encoded as physical features of the image: curvature, length, edges. – Measure in letters since psych studies typically use letters to measure VIS properties. – VIS memory is fleeting, decaying in a few hundreds msecs.
Short Term Sensory Store - AIS • Auditory information store (AIS) – Encoded as physical sound – Size ~ 5 [4.4-6.2] letters – decay ~ 1500 ms [900-3500 ms] – Buffer for physical sound. – Smaller than the VIS (in terms of letters), but lasts longer – seconds, rather than tenths of a second.
Short Term Sensory Store • VIS and AIS are pre-attentional ; i.e., they don’t need the spotlight of attention to focus on them in order to be collected and stored. • Attention can be focused on the visual or auditory stimulus after the fact. • That accounts for phenomena like “What did you say? Oh yeah.”
Processors • Processors have a cycle time (time to accept 1 input, process, & generate 1 output) – Tp ~ 100ms [50-200 ms] (Slowman, Middleman, Fastman) – Tc ~ 70ms [30-100 ms] – Tm ~ 70ms [25-170 ms] • Fastman may be up to 10x faster than Slowman • Cycle times derived from psych studies
Processors • Variation due to humans, stimuli, & conditions • Cognitive processor actually works faster under load! • Playing a video game vs. watching TV. • Cognitive processor is also faster on practiced tasks.
Perceptual Fusion • Two stimuli within the same PP (Perceptual Processor) cycle (Tp ~ 100ms) appear fused. – Like snapping a picture every Tp secs. – If 2 events happen within Tp secs, they will both appear in the picture. – If you move within Tp, you will be fused into a single in-motion element (frame). • Consequences – 1/ Tp frames/sec is enough to perceive a moving picture (10-15 fps OK, 20 fps smooth, 24 fps for movies). – Computer response < Tp feels instantaneous. – Causality is strongly influenced by fusion .
Bottom-up vs. Top-Down Perception • Perception not an isolated process • Bottom-up combines features of stimulus • Top-down uses context • Temporal (audio), spatial (visual) • Draws on long-term memory
Chunking • “Chunk”: unit of perception or memory • Chunks are defined by symbols that represent the activation of past experience. • Depends on presentation and what you already know B M W R C A A O L I B M F B I MWR CAA OLI BMF BIB BMW RCA AOL IBM FBI • 3-4 digit chunking is ideal for encoding unrelated digits
Chunking • Ability to form chunks in working memory depends on how the information is presented – – a sequence of individual letters tend to be chunked as letters – a sequence of three-letter groups tend to be chunked as groups. • It also depends on what we already know. • If the three letter groups are well-known TLAs (three- letter acronyms) we are better able to retain them in working memory.
Chunking Famous study of chess players: • Novices and chess masters were asked to study chess board configurations and recreate them from memory. • The novices could only remember the positions of a few pieces. • Masters could remember entire boards, but only when the pieces were arranged in legal configurations. • When the pieces were arranged randomly, masters were no better than novices. • The ability of a master to remember board configurations derives from their ability to chunk the board, i.e., recognizing patterns from their past experience of playing and studying games.
Attention and Perception • Spotlight metaphor – Used for how attention behaves in perception. – You can focus your attention (PP) on one input channel in your environment at a time. – Channel could be visual or audio field (sound or loc.) • Once you’ve focused your attention on a particular channel, all the stimuli within the area of the “spotlight” are then processed in parallel, whether you mean to or not. • This can cause interference . • Visual dominance : easier to attend to visual channels than auditory channels
Attention and Perception • Say the colors of these words aloud and time yourself: – Book – Pencil – Slide – Window – Car – Hat
Attention and Perception • Do it again: – Green – Orange – Red – Black – Pink – Blue
Attention and Perception • Why is this more difficult the second time?
Attention and Perception Why? • The word which names a different color, interferes with the color we’re trying to say. • This is called the Stroop effect. – Demonstration of interference in the reaction time of a task. – http://en.wikipedia.org/wiki/Stroop_effect • Take away: – Choose the secondary characteristics of our displays – like the multiple dimensions of stimulus, or the context around the stimulus – to reinforce the message of the display, not interfere with it.
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